Electrical safety control circuit for automatic burner equipment



April 17, 1928.

F. FISCHER ET AL ELECTRICAL SAFETY common CIRCUIT FOR AUTOMATIC BURNER EQUIPMENT Filed Aug. 27, 1925 5 Sheets-Sheet 1 IN V EN TORS.

\X ITNESSES.

6am QQMJJW April 17, 192& 1,666,331

F. FISCHER ETAL ELECTRICAL W81! CONTROL CIRCUIT FOR AUTOMATIC BURNER EQUIPMENT Filed A111. 27. 1925 3 Shqtg-Shgqt 2 t E] L 1? FiglXZ WITNESSES. INVENTORS.

April 17, 192a 1,666,331

- F. FISCHER ETAL ELECTRICAL SAFETY CONTROL CIRCUIT FOR AUTOMATIC BURI UBR EQUIXIENT Filed Aux. 27. 1925 3 s am, 3

WITNESSES;

INVENTORS.

45 A specific objemis to rams Ap .11. wa

UNITED um OFFICE.

- ram nacm, OI WONT, m YORK, m ARNOLD MCI! m, OI INTEBLAKIN, I" 338811, MGNOBBIO GRANT OIL 311ml NBPOBATIOI',

OF CORPORATION OI DELAWARE.

- ELEC'IRICAII Bull-Y comm CIRCUIT I'OB AUTOIATIO BURNER ECW- A Application fled a at, mass. ,lq-lal Io. time provement whereby mechanical moving parts subjected to heat are eliminated, andthedevice is operated more completely by electrical means thereby eatly sim li ing, and mcreasing the reliability in li eof the control mechanism.

It is'a well. known property of certain materials which enablesthem to ofier little resistance to the flow of electricity when heated, and a relatively high-resistance when I coolin marked contrast, for instance, to

the electrical conductivity of nickel which decreasesas itstemperature rises. The of current through such material, when once heated, tends tomaintain, the temperature 26 and consequent conductivity of-tlie material,

as in the well known Nernstlamp; but the relation of current to cross-sectional :area may be such as to. avoid this electrical maintenance of conductivity ifdesired;

By inserting in a speciall arranged elec tric circuit, rticles of suc material (certain infusonal-earths, for exam 1c) in locations subjected to the heat pr uced by the burner, pilot light, etc., we obtain a novel 7 :5 electrical OODtIOl'CllClllt which is unusually simple in construction-and safe in operation.

The above described material will herein- I 40 the nature an function of this factor in our invention. i

The generalobject of this inventionis to provide a simple and safe automatical control for burners. i

eliminate all moving parts which are subject to hi h temperature. Another object is to provi e in the circuit a material which is substantially a poorconductor of electricity at room temperasystem again automatically if the s ition .supp fy shoul fail.

tures and a relatively good conductor at high temperatures, in the place of temperature-actuated mechanical contactors.

Another. object is to provide one of these special heat-requiring conductors in pro:-

imity to the pilot-1i ating 1 the burner i goout.

Another object is to provide a heat-reuiring conductor in proximi to the pilothght so as to re-igmte the pilot in case it t so asto prevent operthe pilot light should should go out while current I is passing through the conductor.

Another object is to automatically start the fuel-supply motor and the ignition system of the burner when the circuit is closed by any; means such as a manually operated switch, or a thermostat, boiler control, or-

similar device. c I v Another object is to automatically stop the fuel-su ply motor and the i 'tion system of the urner when the circuit is opened by any means such as a manually operated switch, or a thermostat, boiler control or similar device. v

Another obect is to shut of! the ignition system after burner is lighted- Another object is to start the ition urner ould go out for any reason whatsoever, other than the complete shutdown of the humor. I r h Another object is to shut down the fuelsupply motor and the ignition system automatlcally in a predetermined time if the oil or other fuelhas' failed to ignite.

Another object is to shut down the fuelsup 1y motor and ignition system automat ical y in a predetermined time upon the failure of any one of the elements in the control circuit.

Another-object is to shut down the burner and m automatically if thefuel vent the burner Another object is to ng, after it has shut from automatically starti itself down because of failure-to obtainignition, or failure of any of the elements in the circuit, or failure of the fuel supply as aforesaid,-said shut-down to be maintained until the equipment is inspected and the control manually reset.

Other objects will hereinafter appear.

The nature and scope of this invention are more full explained in the following description ta en in'connection' with the accompanying drawings forming part of the specifications, in which Fig. I is a diagram of our "circuit adapted for alternating'current and provided with placed in a parallel instead of a series circuit.

Similar numbers refer to similar'parts throughout the several figures. In Fig. I, 1 and 2 are alternating current power leads, of any voltage or frequency -2 beingfreferably the grounded side of the line, i the line is grounded. I

j 3 and 4; are terminals of electric motor 5 which drives the pump or other apparatus supplying fuel to the burner. 6 is a solenoid with terminals 7 and 8,'and movable core 9; although a rotary form of motorfcould readily be substituted here for performing the mechanical work of operating a valve, switch, or other ignition apparatus. 6 will therefore be referred to hereafter as the ignition-motor. i

10 is a gas valve operated by ignitionmotor 6. i i

11 to 21 inclusive comprise a time-limit cut-out in which ll'is-a resistance wire or as an ignltlon-motor; 11 to 21 will be reheating coil; 12 is a piece of thermostatic metal with one end fastened rigidly at 13.

and the other end bearing against brass member 14 which is pivoted at 15.

Thermostatic metal 12 is superimposed above the resistance wire or heating-coil 11 and bends upwardwhen heated, as indicated by dotted lines 12. Member 14 is connected through flexible lead 16 to coil 11, and carries contactor 17 which'is held against contactor 18 by the end of thermostatic metal 12.

19 is a compression spring bearing against brass member 14 at one end and against fixed piece 20 at the other. Compression spring 19 provides a quick break between contactors 17" and 18 when thermostatic metal 12 has been heated by coil 11, and has moved above the end of member 14 as indicated by broken lines 12. 9

- 21is a re-setting member which passes through a hole in fixed piece 20," through compression spring 19, and fastens to member 14:. Its purpose is to enable member 14 with its contactor 17, to be pulled over against contactor 18 so as to allow thermostatic metal 12 to spring downward and reset against member 14 when thermostatic metal 12 has cooled sufficiently;

22 to 37 inclusive are parts'of a commercial relay, a thermostat, and a transformer,

allinterconnected for the purpose of automatically closing and opening the power circuit, at predetermined temperatures or presssures. 22 is the relay armature, carrying an insulatedhoolrfor lifting relay arm 23 and 24.

'25 and26 are'contactors on the relay in the main power circuit. 27 and 28 are low voltage contactors'. 29 is an electro-magnet'. 30 is a resistance coil. 31, 32 and 33 are contactor points on a low voltage thermostat. 34 and 35 are theterminals of the secondarywinding of a transformer; .36 and 37 are terminals of'primary winding of the "said transformer. 38 and 39 are terminals of a switch or similar device usually connected mechanically or electrically in some suitable'mann'er totherboiler or furnace or other apparatus which contains the burner, as in, Fig. III.

40 is a selec'ted pieceof infus'orial-earth or heat-requiring conductor above. described,

connected in a shunt circuit around ignitionmo'tor 6'and heating coil 11. 40 may be loferred to as a time-limit cut-out; 22 to 29 Will be referred to as a relay; 31 to 33 will be referred to as a thermostat; 34: to 37 will be referred to as a: boiler-control; and 40 to 41 will be referred to as heat-requiring conductors. \Vhere both heat-requiring conductors are referred to in'thesameclaim, 41 will be designatedas a pilot heat requiring conductor. r I v The descriptive name time-limit cut-out explains the function of this cut-out apparatusywhich functiomis to open an electric circuit" passing through it, and thereby cutout any other apparatus connected in serieswith it, after the lapse of a certain predetermined time constituting the time limit factor. Theoperation of the time- 'limit' cut-out is hereinafter more fully described. 7 I

FigII contains no additional parts over time-limit cut-out, relay, transformer, and

boiler-control switch, may be considered as located on a suitable panel-hoard all enclosed in ametal case or panelbox These parts are enlarged inthe drawing toenable the circuit to be traced more readily.

L. .The fuel-supply motor 5and pump 43 are laced conveniently with relation to. the Boiler or furnace 44. v p .L,

The thermostat is placed lathe articular room or, place, the temperatnreo which, is tobe con'trolled. a 7 Oil supply tank 45 ,is connected by. means of pipe 46 with the pump 43 whichentrains oil from. tank .45 and air -through port 46 and after mixing them in the proper proportions, discharges them through burner supply pipe-.47 andnozzle 48 into the firebox of thefurnacet a 1 Gas 'ilot flame 42 is fed throughgas pipe 49 an gas valve 10, the latter-being. controlled by. solenoid ignition-motor 6. Gas valve 10 permits, when closed, enough leakage of gasto supply the minimum size pilot In Fig. III the boiler-control is shown as a-diaphragm piston I50 connected, through weighted lever51 and or cable 52 passingi over pulleys 53 and 54,. with switch 55; alt ough the whole boilerscontrol apparatus may be installed asa-unit onthetop of the boiler if preferred. y :A practical modificatipnof our circuit is shown inFig. IV in which heat-requiring conductor 41 is connected in ashunt circuit around the heat-coil 11 otthe, time-limit cutout, instead of in series withlthe fuelsupply moton- The operation of our oil-burner control mechanism is es follows: v

The power current is alwayspresumed to be on-,-lines .1 and 2; and pilotfia'me 42 is playing on heat-requiring conductor 41 so that 41 becomes. an element in the main sec c it ssum' t t te tam rotate or pressureof tlg boiler or fma aiis below a predetermined point, above which it is to be maintained, the lowtemperature contacts 31 and 32 of thathermostat, and boiler-control leads 38 and 39 illbe closed. ,The transformer, :usuall of the type to transform the normal 110 v0 t lighting current to a lower voltage (usually24 volts),isener and is thereforein a a. 'tion to supp y current to the relay At epredetermined temperature, the thermostatic member 31 of 1 the thermostat makes contact with 32 which energizesthe. 29 whichin turn pulls solenoid -6 ignited.

from the supply line 2', through heat-requiring conductorytl and fuel-supply motor- 5,

throughfithe solenoid 6, through the tinielimit cut-out, throu h the main contactors complete the .circuit for the current to travel 5 25 and 26 of the re '1 -and backto line 1.

(Heat-requiring con uctor 40 1mm cool, obstructs the flow of currentthrou h it) This forms-a series circuit inflwliich. the breaking to become open and therefore inoperative.

The instant the relay picks up, the motor 5 starts, which in turn starts the pump and thereby opening the gas valve 10; and the heating coil llof the time-limit cut-out begins to heat up. If nothing further takes of any. of the lines or connections in the circu t would cause the entire circuitplace, the heat generated in thecoil 11 of a a the time limit cut-out will cause-thermostatic metal 12;to bend u ward andv pass the end of member 14, This gin turn will allow compression-spring; 19 to, force member 14 out of its lhi Ql'l andbreak contactors 17 valve IO-andthe fuelssupply motor 5 stops,

and 18 WhlCh open the circuit and thereby thereby stopping the flow of oil into the boiler or furnace v V However, when the motor 5 :starts, the

, the, gas valve'lO, and exa-nds the pi e y this gas, valve; so that the fuel oil which is being .sprayedinto thefurnace is thereby Afterignition has taken; lace, the heatrequiring conductor 40 whic is located in .Shunting out thesolenoid in this manner allows the gasralve 10 to close, thereby contracting the pilotto .its. normal position. shunting outitheheating' coil'll permits it to cool down and therefore thermostatic otlight 42,]ivhich is being fed the furnaceflge s'hot and changes its 'charmember- 12 does not move and contactors 1T and 18 cannot be forced apart by compression-springli); and the burner continues to function normally. i

Heat-requiring conductor 40 therefore acts as a monitor over th'e timeI-Iimit cut-out, preventing itfrom functioning or permitting it to function accordingto whether the burnerr is ignited or not ignited respectfullyf and I so should V for anyl electric or; ot

er ignition system which is started in operation by the solenoid 6 should :EailtO Operate, it will be seen that oil will be sprayed into the furnace but-not ignited. Under these circumstances the heat-requir ing conductor 40 would receive'no heat, and conse uently would obstructthe flow of currentt rough it, so that'the current taken to 'o erate the motor would continue to pass t rough the time-limit cut-out (particularly 1 through the heating 'coil 11) and through the solenoid 6." The heat generated" in the resistance wire of heating coil 11 under these circumstances would be suffitienhin a'predetermined time, to cause'thermostatic member 12 to move upwardallowing compression-spring 19to act and breakthe contact at 17 "and 18 and thereby open the circuit and shutdown all of the apparatus.

If the burner should be functioning normally and the oil supply should become exhausted, combustion would of course cease. This would i allow heat-requiring conductor 40 to cool and resist the flow of current through its shunt circuit,so that all of the current taken by the motor would pass through the coil'll of the time-limit cut-out plained above. i

, After sufiicient current is flowing'through heat-requiring conductor 41, the heat produced by the current renders it incandescent and the apparatus would shutdown as ex- "and thereby maintains its electrical, c'onductivity. If the 'gas pilot should go out, for any reason after the burner is ignited-,the' heat generated by the current passing through heat-requiring conductor 41 is suflicient to maintain the conductivitybfthe conductor, and to re-i' 'te the gaspilot. If, on the other 1 hand, 'tfie pilot should 'go out before the relay closes, *then the main 'cir cu-itwill remain 'opensince' the necessary current cannot flowthrough heat-requiring conductor 41 when thela'tter is relatively cool.

, Ifthe pilot should go outwith the circuit arranged as'shown in'FignIV, most otthe current would be shunted through heat-coil 11 of the time-limit cut-out so that the timelimit cut-out would open the circuit and shut down'the fuel-supply motor in ashort predetermined time as previously described.

"Ourcircuit may be, used without heat-requiring conductor 41,'in which case the time limit. cut-out will ,shut down the burner in p a short predetermined time, as previously described, if the pilot should go out and ignition should fail for this'or any other reason, ,l

It is to be understood that this invention reason "fail to expand, or the forth.

ment of parts shown in the accompanying drawings, but i that modification therein may be 'made'without' departing from the spirit of the invention. i 3

We are: aware that prior to our invention, relays, solenoids, and various forms of thermostatic-controls have-been used commercially for sundry purposes, and do not claim these individualcircuits or parts in ,detail; but 'we'do believe ourselves to be the first to make use ofhe'at-re uiring conductorsiin the manner and -for1- t e purposes herein set We claim:-- In an electrical control circuit for. burners having gas ignition pilots, a fuelsupply motor, the conductorb'eing located adjacent to the pilotso as to be heated and thereby rendered conductive b the pilot when the pilot 1s ignited, the con uctor being connected'in series with the motor so that themotor cannot startfwhen the pilot isnot ignited, the conductor being so proportioned as tofbe heated by' curr'ent passing through it; and thereby maintained in a conductive state independently of the pilot when] the motor and conductor are energized so that the out while the motor and conductor are energized. Iv

In a control circuit for burners having gas i'gnition pilots, a fuel-supplymotor, a heat-requiringconductor, the conductor being located adjacent to the'pilot sofas to be heated and thereby rendered the pilot when the pilot is ignited, the conductor being connected in series with the motor, so that the motor can start when the pilot is ignited, the conductor being so proportione as'to be maintained in a state of lncandescence bythe flow of current through it when the motor is energized so that the incandescent conductor will re-ignite the pilot if the, pilot "goes out'while the motor is energized. a

3; In an electrical control circuit for 'burner's having ignition pilots, a fuel-supply motor, a heat-requiring conductor located adjacent to the pilot so as'to be heated and thereby rendered-conductive by the pilot when the pilot is ignited, the conductor being connectedin series in the connot ignited, the conductor "being so proportioned as to he -heatedby current passing through itandthereb'y maintained in a conductive jstatleindependently of the pilot when the conductor, is energized, so that the circuit will remain closed andthe motor will continue to run if the pilot goes out whilethe conductor is energized.

4. In a control deviceforburners, afuelsupply motor, a motor control circuit, a gas a heat-requiring conductor,

motor willcontinue torun ifthe pilot goes conductive by ignition pilot, a heat-requiring conductor not ignited, the conductor being so propor- Iiocsted adjacent to the pilot so as to be tioned as to be maintained in a, state of inheated and. thereby rendered conductive by candescence by the flow of current through 10 the pilot when the pilot is ignited, the conit so as to re-ignite the pilot if the pilot 5 ductor being connected in series in the congoes out while the conductor is energized. trol circuit so as to open the circuit and pre- FRANK FISCHER.

vent starting the motor when the pilot is ARNOLD FRANCIS VAN PELT. 

